A batch washing machine can comprise a tubular wash trommel or drum which is divided into individual wash chambers, more particularly containing a screw or worm conveyor which forms the individual wash chambers. The individual wash process is performed by reversing partial rotations of the wash trommel and the transport of a batch of wash into the next one of the wash chambers occurs by more than one complete rotation of the wash trommel.
In German Utility Pat. No. 1 894 718 a batch washing machine is described. The individual batches of wash are fed in at one end of the wash trommel and discharged from the other end. According to the pitch of the screw conveyor a wash chamber is formed for each of the batches of wash. The individual wash process is performed by reversing rotary motion of the wash rommel of less than 360.degree., advantageously of about 300.degree., while the transport of the batches of wash into the following chamber is effected through more than a complete rotation of the trommel in the same direction.
The individual chambers form a prewash zone, a clear wash zone and a rinsing zone in which different modes of action to supply and remove water, washing means and chemicals are provided to perform the optimum wash process. It is necessary to provide the corresponding chambers with an outer trommel (German Pat. No. 30 40 309) at considerable expense or effort.
Frequently it is necessary to reduce the water flow in the final chamber of the rinsing zone which is simultaneously the last chamber of the entire machine. This is the case when a starching is required in this chamber or when other expensive chemicals such as finishing chemicals must be provided. The water level commonly used in rinsing is then much too high to attain a satisfactory result with an economical use of the starching, softening or finishing chemicals.
It is thus desirable to reduce the water level from say 6 liter/kg dry wash to only 3 liter/kg dry wash. It is also necessary to completely remove the water when the rinsing process is again repeated in the same chamber.